ANALYTICAL ABSTRACTS. 20/ 



theory of the origin of the transverse valleys through backward erosion and 

 tapping, as suggested by Heim. Wind gaps representing the backward ero- 

 sion in various stages ought to exist all over the Jura Mountains, which is 

 contrary to fact. " This theory is particularly at fault when the strange grouping 

 of the cross valleys along li7ies transverse to the folds is observed." 5. Their 

 origin from superimposition is impossible, as the geological conditions required 

 were evidently never present. 6. Mr. Foerste considers them of antecedent 

 origin, and says : "Although the direct evidence of the progressive erosion 

 of the streams during the rising of the folds is lacking, the systematic arrange- 

 ment of several series of the transverse valleys in straight lines is -strongly 

 suggestive of the antecedent origin of the streams. This and the failure of 

 other explanations to meet the facts are the main support of the theory." 



Professor Davis notes the bearing of these conclusions on his assumption 

 that the Appalachian streams were consequent. The consequent origin of the 

 Jura streams was cited in support of this assumption. In view of Mr. 

 Foerste's conclusions. Professor Davis withdraws the assumption that the 

 " Appalachian streams were necessarily consequent upon the structure of the 

 mountains when they were young," but still thinks that they probably were 

 because the deformation of the Appalachians was so much stronger than 

 that of the Jura. C. E. P. 



Deep-Sea Sounding. By Captain A. S. Barker, U.S.N. (New York : 

 John Wiley & Sons, 133 pp. 3 maps). 



This volume gives a brief account of the work done by U. S. S. Enter- 

 prise in deep-sea sounding on a cruise from Norfolk, Va., to China and return. 

 The route taken was via Cape de Verde Islands, Cape of Good Hope, along 

 the coast of South Africa, thence to Madagascar, the Comoro Islands and 

 Zanzibar, thence across the Indian Ocean to the straits of Sunda, thence to 

 China. Soundings were taken every 100 miles, and sometimes oftener. On 

 the return voyage a line of soundings was made from Wellington, New Zea- 

 land to Magellan Straits, and from Montevideo northward off the east coast of 

 South America, at varying distances, as far north as the Bermudas. 



On charts accompanying the volume are recorded the depth of the sound- 

 ings and data concerning the nature of the material of the sea bottom. The 

 deepest sounding was 4,529 fathoms, made to the north of Porto Rico, the 

 position being within forty miles of the deepest sounding (4,561 fathoms) 

 ever taken in the Atlantic Ocean. Two submarine peaks were discovered in 

 the South Atlantic Ocean about 20° west of Cape Town, at a depth of 731 

 and 979 fathoms. The materials brought up wei'e corals, sand and shells. 

 About 20° east north-east of Montevideo an extensive sand bank was found at 

 a depth of 390 to 500 fathoms. The text is made up of extracts from the ship's 

 log and the captain's private journal. C. E. P. 



